1. Field of the Invention
The present invention relates to a station-side apparatus of a wavelength multiplexing optical access network, a wavelength and network address allotting method executed by the station-side apparatus, and a program thereof. More specifically, the present invention relates to a station-side apparatus of a wavelength division multiplexing PON (Passive Optical Network) system, a wavelength and network address allotting method in the system, and a program thereof.
2. Description of the Related Art
It has been a big issue to achieve broadband of the access circuits due to a rapid spread of the Internet. Various systems such as ADSL, cable modems, and the like have already been put into practical use as the broadband access circuits. However, the passive optical network (PON) has drawn an attention for achieving a still broader band.
The PON is a network where a plurality of users share a single optical fiber by using an optical splitter provided in the middle of the paths. In general, an in-home apparatus (hereinafter, referred to as an ONU: Optical Network Unit) is placed at an end user's home, and a station-side apparatus (hereinafter, referred to as an OLT; Optical Line Terminator) is placed at the station. Both apparatuses are connected through an optical fiber and an optical splitter.
A personal computer of each user is connected to a network through the ONU, which is connected further to a higher network and the Internet through the OLT. The wavelengths of upstream signal (the wavelength is normally 1.3 μm band) and the downstream signal (the wavelength is normally 1.5 μm band) are multiplexed, so that it is possible to connect in both directions by the optical fiber with a single core. Furthermore, recently, there has been a research carried out on a wavelength multiplexing PON that can allot an individual wavelength to each ONU by utilizing a technique of the wavelength division multiplexing (WDM) (For example, “Broadcast digital video delivered over WDM passive optical networks” Iannone, P. P.; Reichmann, K. C.; Frigo, N. J.; Photonics Technology Letters, IEEE Volume 8, Issue 7, July 1996 pp. 930-932 (Non-Patent Literature 1)).
Further, DHCP is known as a client-server type protocol which automatically sets the network parameter. This protocol dynamically allots and informs the parameter such as an IP address to each client when starting up the apparatus, and retrieves the allotted parameter such as the IP address when shutting down the apparatus (For example, IETF Document RFC2131, RFC2132, Dynamic Host Configuration Protocol (Non-Patent Literature 2)).
Incidentally, in a conventional wavelength multiplexing PON system, the wavelength of the optical signal is set manually through a switch of the apparatus or through the operation system. Thus, there requires a lot of work, so that there may generate a setting error. Further, it is necessary to predetermine the correlation between the signal and the wavelength statically. Furthermore, for performing communication, it is necessary to set the network addresses to each ONU, and the setting thereof needs to be performed separately from the setting of the wavelength. This leads to a complication and an increase in the setting time. In addition, it leads to wasting the wavelength resources, since the wavelength is also allotted to the ONUs that are not being used. Moreover, the complication of the setting and the work required therefore are more increased in the case where a plurality of wavelengths are allotted to a single ONU as necessary.